In order to evaluate the normal physiology of the maternal venous circulation, Doppler examinations of the venous system in the right inferior extremity and suprainguinal part of the common femoral vein were carried out in 38 healthy pregnant women, in 12 non-pregnant controls and in 16 women at early puerperium. ...

The objective of this study was to describe blood flow velocity waveforms of fetal peripheral pulmonary arteries in normally grown and growth-retarded fetuses. Doppler studies were performed in 182 normally grown fetuses (gestational age 18-40 weeks) and in 61 growth-retarded fetuses (gestational age 24-36 weeks) that were free from structural ...

True knot of the umbilical cord is a rare occurrence, which is difficult to diagnose antenatally, even with the use of ultrasound. Constriction of a true knot of the umbilical cord may lead to obstruction of the fetal circulation and subsequent intrauterine death. We present a singleton pregnancy, in which ...

Vasoactive prostaglandins have been reported to mediate umbilical/placental blood flow in humans. Since it has been suggested that cocaine exerts its teratogenic action via vasoconstriction and a corresponding reduction in blood flow, it is reasonable to hypothesize that cocaine influences the vasoactive prostaglandins such that blood flow would be affected. ...

Ultrasonographic measurement of umbilical venous blood flow as a reflection of placental blood flow has been used for assessment of fetal well-being. Because fetal and maternal factors may prevent satisfactory measurement of umbilical venous diameter and flow velocity, an alternative method would be helpful. We found that, in 35 human ...

OBJECTIVE: Umbilical cord blood gases and acid-base data from vigorous neonates were examined to determine normal values and ranges. STUDY DESIGN: The University of California, San Francisco, Perinatal Data Base was used to retrieve information from deliveries between 1977 and 1993. Newborns with 5-minute Apgar scores > or = 7 ...

The objective of this study was to assess the value of Doppler indices calculated from the inferior vena cava and ductus venosus in the identification of acidemia and hypoxemia as determined by pH and gas analysis of fetal blood obtained by cordocentesis in growth-retarded fetuses. Doppler measurements were performed in ...

OBJECTIVES: To assess ductus arteriosus velocity waveforms in the appropriate and small-for-gestational-age (SGA) fetuses. STUDY DESIGN: Ductus arteriosus flow velocity waveforms were obtained in 14 normal fetuses in a longitudinal study and in 139 normal fetuses in a cross-sectional study with pulsed and continuous Doppler ultrasonography. Ductus velocity waveforms were ...

OBJECTIVE: Our purpose was to measure umbilical blood flow continuously by use of a transit time ultrasonic flow transducer and to compare the blood flow measurements with the steady-state diffusion method in the chronic fetal sheep preparation. STUDY DESIGN: We compared umbilical blood flow measurements calculated by the steady-state diffusion ...

OBJECTIVE: Measuring blood pH in the umbilical artery at birth is an important means of maintaining obstetrical quality. Consideration of the interrelations between low umbilical blood pH and perinatal risk factors may enable obstetricians to provide better care of the mother and child during pregnancy and delivery. We therefore studied ...

This study was performed to investigate whether fetal blood sampling and/or transplacental puncture are associated with changes of blood flow velocity waveforms in umbilical artery and fetal circulation. The pulsatility index (PI) was measured from umbilical artery, thoracic descending aorta, renal artery, and middle cerebral artery immediately before and after ...

High perinatal mortality has been reported in association with the finding of absent end-diastolic flow velocities in the umbilical artery. The fetus is known to centralize its circulation during hypoxemia and abnormal venous blood flow velocities have been reported in cases of heart failure and imminent asphyxia. The aim of ...

OBJECTIVE: To investigate whether bolus injection of dehydroepiandrosterone sulfate (DHAS) is associated with changes in fetal middle cerebral artery flow velocity waveforms in term pregnancy. METHODS: Ten normal full-term pregnant women received the administration of a 200-mg intravenous dose of DHAS in 20 ml of 5% dextrose. Ten normal full ...

In a retrospective analysis of the standard protocols for fetal echocardiographic examination, 27 fetuses (mean gestational age 29 +/- 5.4 weeks) with ascites were evaluated. Fetal cardiomegaly (increased heart area/chest area ratio), the presence or absence of atrioventricular valve regurgitation, inferior vena cava and ductus venosus Doppler flow velocity and ...

OBJECTIVE: To ascertain whether the perinatal cerebral blood flow velocity differed between vaginally delivered appropriate for gestational age (vag. AGA) term babies, AGA babies delivered by Caesarean section (C.s. AGA), and small for gestational age (C.s. SGA) babies also delivered by Caesarean section. STUDY DESIGN: Forty-five babies were examined by ...

The purpose of this study was to evaluate the effects of a prophylactic intravenous bolus of ephedrine on the incidence and severity of maternal hypotension and on neonatal outcome. Term healthy parturients (n = 122) scheduled for elective repeat cesarean section under regional anesthesia were studied. Ninety-two women received 10 ...

BACKGROUND: Previous techniques for the study of the fetal circulation did not permit assessment of phasic events associated with the cardiac cycle. We used multimodal ultrasound techniques to examine flow events that occur in the major veins and across the foramen ovale in the circulation of the fetal lamb. METHODS ...

BACKGROUND: Doppler velocimetry, a new tool for measuring blood flow, vascular resistance, and central hemodynamics can be applied to monitor those patients at risk and provide therapeutic concepts for preeclampsia. This study was designed to use a Doppler velocimetry study to correlate the relationship between central hemodynamics, uteroplacental circulation, and ...

The hemodynamic changes in the uteroplacental circulation and the umbilical artery were evaluated in normal pregnancy from 8 to 14 weeks' gestation. A 6-9-MHz broad-band transvaginal sonographic transducer combined with pulsed color Doppler was used to scan 37 healthy volunteer pregnant women at weekly intervals. Vascular impedance to blood flow ...

OBJECTIVES: The aims of the present study are (1) to determine the erythrocyte CAI and CAII concentrations in SGA and anemic fetuses and to compare them with normal levels, and (2) to examine whether there is any correlation between fetal hypoxia or anemia and isoenzyme concentrations. METHODS: Human erythrocyte CAI ...

Vascular impedance is defined as the ratio between the frequency components of the local blood pressure waveform and those of the local blood volume flow waveform. Assessment of vascular impedance is, for example, important to study heart load and distal vascular bed vasomotricity. However, only a few studies on vascular ...

We report four cases of uteroplacental insufficiency with severe intrauterine growth retardation in which coronary blood flow was demonstrated by means of color-coded and pulsed wave Doppler sonography. Intrauterine fetal compromise was indicated by pathological uterine and umbilical flow indices and decreased impedance in the cerebral vasculature. Later, this was ...

To test the hypothesis that intrauterine growth restriction (IUGR) would lead to altered neurotransmitter metabolism in the brain because of poorer oxygenation, blood flows and tissue concentrations of noradrenaline, dopamine, serotonin and their metabolites were measured in 14 parts of the brain of guinea-pig fetuses at 61-64 days' gestation. Eight ...

The abnormal umbilical artery Doppler waveform represented by absent end-diastolic flow velocity (AEDFV) identifies a group of preterm small-for-gestational age fetuses that are at high risk of perinatal death due to chronic fetal hypoxia. The placental ischaemia that results from inadequate trophoblast invasion of spiral arterioles leads to an assumption ...

Fifteen years after its introduction in obstetrics, Doppler sonography can now be considered to be more than a useful tool in differentiating fetuses at low or high risk for adverse perinatal outcome. In compromised fetuses, it allows very reliable assessment of the actual condition of the fetus in the cascade ...

OBJECTIVE: The aim of this study was to evaluate the relationship between uteroplacental circulatory insufficiency and the fetoplacental release of adenosine in pregnancies complicated by preeclampsia. STUDY DESIGN: We performed uterine artery Doppler velocimetry and calculated the pulsatility index of the uterine artery, to detect uteroplacental circulatory insufficiency, immediately before ...

The objective of this study was to analyze the effects of cordocentesis on velocity waveforms recorded from the inferior vena cava and to evaluate differences, if any, in the hemodynamic response between normally grown and growth-retarded fetuses. Twenty-five normally grown fetuses and 20 growth-retarded fetuses were considered for this study. ...

This paper summarizes our experience with Doppler velocimetry in survivors of intrauterine co-twin demise. In the first trimester, ten dichorionic deaths occurred; none of the survivors developed flow disorders. During the second trimester, there were three intrauterine demises, two of them were monochorionic and the survivors developed flow disorders: one ...

OBJECTIVE: The purpose of this study was to determine oxygen free radical activity in the neonate at birth and relate it to umbilical cord blood acid-base status. STUDY DESIGN: A series of 110 singleton deliveries had determination of two lipoperoxides in umbilical cord blood: malondialdehyde and organic hydroperoxide. Umbilical pH, ...

Twenty-two hospitalized patients, diagnosed as having hypertensive disorder of pregnancy, were selected from two University Clinics. Maternal serum samples were analyzed for serum group II phospholipase A2 (PLA2-II) by time-resolved fluoroimmunoassay. At the same time, umbilical artery blood flow velocities were measured with color Doppler sonography for orientation and pulsatile ...

OBJECTIVE: To determine if antenatal vitamin K and phenobarbital therapy affect coagulation studies in umbilical blood at birth, and to provide 95% reference ranges for umbilical blood coagulation parameters in premature gestations. METHODS: Patients at imminent risk for spontaneous or indicated premature delivery less than 34 weeks' gestation were randomized ...

OBJECTIVE: To quantitate umbilical vascular coiling antenatally, and to correlate the coiling index with Doppler flow characteristics in umbilical vessels. METHODS: We studied 45 normal term fetuses within 24 hours before delivery. The umbilical coiling index was calculated using sonographic longitudinal views of cord vessels from several segments antenatally, and ...

We report a statistical analysis of 893 high-risk patients who underwent Doppler sonographic estimation of umbilical venous blood flow within 2 weeks of delivery. Patients with red cell isoimmunization were excluded. In a total of 84 patients, the umbilical venous flow rate was above the 95th centile for normal pregnancy. ...

This study was designed to determine the effect of the mode of delivery on the in vitro assessment of placental blood vessel function. Twenty-two subjects with uncomplicated pregnancies, normal antenatal Doppler flow velocity waveforms and normal birth weights were recruited for the study. The 11 subjects who were delivered by ...

The objective of this study was to evaluate the effect of fetal blood sampling on cardiac flow velocity waveforms. Flow velocity waveforms were measured from the ascending aorta and pulmonary artery immediately before and after fetal blood sampling in 29 normally grown and 12 growth-retarded fetuses. The latter group was ...

OBJECTIVE: To examine the relationship between trisomy and neonates with noncoiled umbilical blood vessels. STUDY DESIGN: The incidence of and risk factors for trisomy were evaluated among 48 consecutive, live-born neonates with noncoiled umbilical vessels. RESULTS: Four cases (8.3%) of trisomy were identified. One case of mosaicism was also noted ...

OBJECTIVE: To determine if the increase in cerebral blood flow ("brain-sparing" effect) with fetal hypoxemia is associated with discordant hemodynamics in the upper extremities. METHODS: We studied 12 fetuses with severe growth retardation, absent or reverse end-diastolic blood flow in the umbilical artery, and low pulsatility index (PI) in the ...

OBJECTIVE: The purpose of this study was to determine the developmental changes in blood flow to the network of fetal microvessels in ovine chorion and amnion. METHODS: Colored microspheres (15.10 +/- 0.02 [standard deviation] mu in diameter) were infused into the superior vena cava in nine chronically catheterized fetal sheep ...

OBJECTIVE: To determine whether sonographic assessments of increasing placental maturity are associated with changes in the theoretical diffusing capacity of the organ and with changes in vascular resistance. DESIGN: Placental maturity was assessed sonographically in 10 organs: five were classified as completely immature and five as completely mature. Doppler flow ...

The umbilical artery, aorta, and middle cerebral artery pulsatility indices were investigated by pulsed Doppler ultrasound in 73 fetuses at 18-37 weeks of gestation, before and after fetal blood sampling performed either at the placental cord insertion (n = 46) or at the intrahepatic vein (n = 27). At the ...

OBJECTIVE: Our purpose was to determine whether postterm patients with oligohydramnios differ in their fetal and umbilical blood flow distribution from those with a normal volume of amniotic fluid. STUDY DESIGN: Pulsed-wave Doppler imaging was used prospectively to determine the resistance index in the fetal middle cerebral, renal, and umbilical ...

Indomethacin lowers fetal and neonatal brain blood flow and may reduce the risk of periventricular-intraventricular hemorrhage. However, concerns have been raised that cerebral O2 metabolism may be compromised at lower cerebral perfusion pressures. In 17 near-term lamb fetuses, changes in brain blood flow and cerebral O2 metabolism (CMRO2) were measured ...

OBJECTIVE: To assess impedance to blood flow through spiral arteries in the central and peripheral areas of the placental bed, to determine if in vivo findings are in concordance with histologic observations of cytotrophoblast invasion. METHODS: This study was cross-sectional, using transabdominal color flow and pulsed Doppler imaging in 64 ...

OBJECTIVE: Our purpose was to investigate arterial, venous, and intracardiac blood flow in growth-retarded fetuses and to relate the Doppler results to blood gases in umbilical venous blood obtained by cordocentesis. STUDY DESIGN: A cross-sectional, pulsed-wave color Doppler ultrasonographic study of 23 severely growth-retarded fetuses undergoing cordocentesis and measurement of ...

Studies in the fetal lamb have shown that atrial pacing beyond a rate of 300-320 beats/min may be associated with dramatic changes of venous blood velocity waveforms, an increase of venous pressure by up to 75%, hydrops, polyhydramnios and placental edema. The aim of our study was to determine the ...

Cardiac tamponade occurs very rarely, but is life-threatening in the newborn. This paper reports a premature newborn who developed profound shock 25 hours after undergoing umbilical venous catheterization. Echocardiography taken later, showed marked pericardial effusion. An umbilical venous catheter was located in the left atrium. Immediate pericardiocentesis was performed, 11 ...

This study on the human umbilical artery was undertaken in order to elucidate possible correlations between changes in response to vasoactive substances in vitro and abnormal umbilical artery flow velocity waveforms in vivo associated with preeclampsia and intrauterine growth retardation. The vascular reactivity to endothelin-1, noradrenalin, serotonin, the thromboxane A2 ...

In 29 pregnancies complicated by maternal diabetes mellitus paired samples of umbilical venous blood were obtained at cordocentesis and delivery to investigate the effect of delivery on indices of fetal oxygenation. After delivery by elective Caesarean section the median umbilical venous blood pH was significantly lower than predelivery, however, there ...

Using the Doppler technique, this study compared the prenatal and postnatal flow patterns of an infant with cerebral arteriovenous (AV) malformation. Fetal right ventricular end-diastolic dimension was 1.7 cm with right ventricular ejection equaling 66% of the combined cardiac output. Diastolic flow was reversed in the fetal aortic isthmus but ...

OBJECTIVE: To correlate the peak velocities of the aortic outflow tract of growth-retarded fetuses with fetal acid base status and oxygenation measured in utero. METHODS: Thirty-one growth-retarded fetuses with abnormal umbilical pulsatility index (PI) measurements underwent fetal blood sampling. Blood pH, carbon dioxide pressure (PCO2), oxygen pressure (PO2), oxygen saturation, ...